Hope lad's cultivated lily (8)
I believe the answer is:
asphodel
'lily' is the definition.
(I've seen this before)
'hope lad's cultivated' is the wordplay.
'cultivated' indicates anagramming the letters.
'hope'+'lads'='hopelads'
'hopelads' with letters rearranged gives 'ASPHODEL'.
(Other definitions for asphodel that I've seen before include "Mediterranean plant" , "Lad hopes (anag) - flower" , "blooms from Elysian fields" , "Lily-like plant, the flower of death to ancient Greeks" , "Plant of lily family - lop heads (anag)" .)